Re: [PATCH v2] mini-os: netfront: Handle init failure when no vifs are provided

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Costin Lupu, le sam. 28 nov. 2020 14:44:38 +0200, a ecrit:
> These changes deal with the case when no vifs are created. This can happen 
> when
> no vif is provided in the config file for mini-os images with netfront 
> support.
> 
> Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>

Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

> ---
>  lwip-net.c | 4 ++++
>  netfront.c | 9 +++++++--
>  2 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/lwip-net.c b/lwip-net.c
> index 7e0d871..16950d3 100644
> --- a/lwip-net.c
> +++ b/lwip-net.c
> @@ -348,6 +348,10 @@ void start_networking(void)
>    tprintk("Waiting for network.\n");
>  
>    dev = init_netfront(NULL, NULL, rawmac, &ip);
> +  if (!dev) {
> +      tprintk("Error initializing netfront.\n");
> +      return;
> +  }
>    netmask_str = netfront_get_netmask(dev);
>    gw_str = netfront_get_gateway(dev);
>    
> diff --git a/netfront.c b/netfront.c
> index 2075410..f927e99 100644
> --- a/netfront.c
> +++ b/netfront.c
> @@ -383,6 +383,7 @@ char *netfront_get_gateway(struct netfront_dev *dev)
>  
>  static struct netfront_dev *_init_netfront(struct netfront_dev *dev)
>  {
> +    int domid;
>      xenbus_transaction_t xbt;
>      char* err = NULL;
>      char* message=NULL;
> @@ -393,6 +394,12 @@ static struct netfront_dev *_init_netfront(struct 
> netfront_dev *dev)
>      int i;
>      char path[256];
>  
> +    snprintf(path, sizeof(path), "%s/backend-id", dev->nodename);
> +    domid = xenbus_read_integer(path);
> +    if (domid < 0)
> +        return NULL;
> +    dev->dom = domid;
> +
>      printk("net TX ring size %lu\n", (unsigned long) NET_TX_RING_SIZE);
>      printk("net RX ring size %lu\n", (unsigned long) NET_RX_RING_SIZE);
>      init_SEMAPHORE(&dev->tx_sem, NET_TX_RING_SIZE);
> @@ -407,8 +414,6 @@ static struct netfront_dev *_init_netfront(struct 
> netfront_dev *dev)
>          BUG_ON(dev->rx_buffers[i].page == NULL);
>      }
>  
> -    snprintf(path, sizeof(path), "%s/backend-id", dev->nodename);
> -    dev->dom = xenbus_read_integer(path);
>  #ifdef HAVE_LIBC
>      if (dev->netif_rx == NETIF_SELECT_RX)
>          evtchn_alloc_unbound(dev->dom, netfront_select_handler, dev, 
> &dev->evtchn);
> -- 
> 2.20.1
>